archival/libarchive/open_transformer.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   4  */
   5
   6 #include "libbb.h"
   7 #include "bb_archive.h"
   8
   9 void FAST_FUNC init_transformer_state(transformer_state_t *xstate)
  10 {
  11         memset(xstate, 0, sizeof(*xstate));
  12 }
  13
  14 int FAST_FUNC check_signature16(transformer_state_t *xstate, unsigned magic16)
  15 {
  16         if (!xstate->signature_skipped) {
  17                 uint16_t magic2;
  18                 if (full_read(xstate->src_fd, &magic2, 2) != 2 || magic2 != magic16) {
  19                         bb_error_msg("invalid magic");
  20                         return -1;
  21                 }
  22                 xstate->signature_skipped = 2;
  23         }
  24         return 0;
  25 }
  26
  27 ssize_t FAST_FUNC transformer_write(transformer_state_t *xstate, const void *buf, size_t bufsize)
  28 {
  29         ssize_t nwrote;
  30
  31         if (xstate->mem_output_size_max != 0) {
  32                 size_t pos = xstate->mem_output_size;
  33                 size_t size;
  34
  35                 size = (xstate->mem_output_size += bufsize);
  36                 if (size > xstate->mem_output_size_max) {
  37                         free(xstate->mem_output_buf);
  38                         xstate->mem_output_buf = NULL;
  39                         bb_perror_msg("buffer %u too small", (unsigned)xstate->mem_output_size_max);
  40                         nwrote = -1;
  41                         goto ret;
  42                 }
  43                 xstate->mem_output_buf = xrealloc(xstate->mem_output_buf, size + 1);
  44                 memcpy(xstate->mem_output_buf + pos, buf, bufsize);
  45                 xstate->mem_output_buf[size] = '\0';
  46                 nwrote = bufsize;
  47         } else {
  48                 nwrote = full_write(xstate->dst_fd, buf, bufsize);
  49                 if (nwrote != (ssize_t)bufsize) {
  50                         bb_perror_msg("write");
  51                         nwrote = -1;
  52                         goto ret;
  53                 }
  54         }
  55  ret:
  56         return nwrote;
  57 }
  58
  59 ssize_t FAST_FUNC xtransformer_write(transformer_state_t *xstate, const void *buf, size_t bufsize)
  60 {
  61         ssize_t nwrote = transformer_write(xstate, buf, bufsize);
  62         if (nwrote != (ssize_t)bufsize) {
  63                 xfunc_die();
  64         }
  65         return nwrote;
  66 }
  67
  68 void check_errors_in_children(int signo)
  69 {
  70         int status;
  71
  72         if (!signo) {
  73                 /* block waiting for any child */
  74                 if (wait(&status) < 0)
  75 //FIXME: check EINTR?
  76                         return; /* probably there are no children */
  77                 goto check_status;
  78         }
  79
  80         /* Wait for any child without blocking */
  81         for (;;) {
  82                 if (wait_any_nohang(&status) < 0)
  83 //FIXME: check EINTR?
  84                         /* wait failed?! I'm confused... */
  85                         return;
  86  check_status:
  87                 /*if (WIFEXITED(status) && WEXITSTATUS(status) == 0)*/
  88                 /* On Linux, the above can be checked simply as: */
  89                 if (status == 0)
  90                         /* this child exited with 0 */
  91                         continue;
  92                 /* Cannot happen:
  93                 if (!WIFSIGNALED(status) && !WIFEXITED(status)) ???;
  94                  */
  95                 bb_got_signal = 1;
  96         }
  97 }
  98
  99 /* transformer(), more than meets the eye */
 100 #if BB_MMU
 101 void FAST_FUNC fork_transformer(int fd,
 102         int signature_skipped,
 103         IF_DESKTOP(long long) int FAST_FUNC (*transformer)(transformer_state_t *xstate)
 104 )
 105 #else
 106 void FAST_FUNC fork_transformer(int fd, const char *transform_prog)
 107 #endif
 108 {
 109         struct fd_pair fd_pipe;
 110         int pid;
 111
 112         xpiped_pair(fd_pipe);
 113         pid = BB_MMU ? xfork() : xvfork();
 114         if (pid == 0) {
 115                 /* Child */
 116                 close(fd_pipe.rd); /* we don't want to read from the parent */
 117                 // FIXME: error check?
 118 #if BB_MMU
 119                 {
 120                         IF_DESKTOP(long long) int r;
 121                         transformer_state_t xstate;
 122                         init_transformer_state(&xstate);
 123                         xstate.signature_skipped = signature_skipped;
 124                         xstate.src_fd = fd;
 125                         xstate.dst_fd = fd_pipe.wr;
 126                         r = transformer(&xstate);
 127                         if (ENABLE_FEATURE_CLEAN_UP) {
 128                                 close(fd_pipe.wr); /* send EOF */
 129                                 close(fd);
 130                         }
 131                         /* must be _exit! bug was actually seen here */
 132                         _exit(/*error if:*/ r < 0);
 133                 }
 134 #else
 135                 {
 136                         char *argv[4];
 137                         xmove_fd(fd, 0);
 138                         xmove_fd(fd_pipe.wr, 1);
 139                         argv[0] = (char*)transform_prog;
 140                         argv[1] = (char*)"-cf";
 141                         argv[2] = (char*)"-";
 142                         argv[3] = NULL;
 143                         BB_EXECVP(transform_prog, argv);
 144                         bb_perror_msg_and_die("can't execute '%s'", transform_prog);
 145                 }
 146 #endif
 147                 /* notreached */
 148         }
 149
 150         /* parent process */
 151         close(fd_pipe.wr); /* don't want to write to the child */
 152         xmove_fd(fd_pipe.rd, fd);
 153 }
 154
 155
 156 #if SEAMLESS_COMPRESSION
 157
 158 /* Used by e.g. rpm which gives us a fd without filename,
 159  * thus we can't guess the format from filename's extension.
 160  */
 161 static transformer_state_t *setup_transformer_on_fd(int fd, int fail_if_not_compressed)
 162 {
 163         union {
 164                 uint8_t b[4];
 165                 uint16_t b16[2];
 166                 uint32_t b32[1];
 167         } magic;
 168         transformer_state_t *xstate;
 169
 170         xstate = xzalloc(sizeof(*xstate));
 171         xstate->src_fd = fd;
 172         xstate->signature_skipped = 2;
 173
 174         /* .gz and .bz2 both have 2-byte signature, and their
 175          * unpack_XXX_stream wants this header skipped. */
 176         xread(fd, magic.b16, sizeof(magic.b16[0]));
 177         if (ENABLE_FEATURE_SEAMLESS_GZ
 178          && magic.b16[0] == GZIP_MAGIC
 179         ) {
 180                 xstate->xformer = unpack_gz_stream;
 181                 USE_FOR_NOMMU(xstate->xformer_prog = "gunzip";)
 182                 goto found_magic;
 183         }
 184         if (ENABLE_FEATURE_SEAMLESS_Z
 185          && magic.b16[0] == COMPRESS_MAGIC
 186         ) {
 187                 xstate->xformer = unpack_Z_stream;
 188                 USE_FOR_NOMMU(xstate->xformer_prog = "uncompress";)
 189                 goto found_magic;
 190         }
 191         if (ENABLE_FEATURE_SEAMLESS_BZ2
 192          && magic.b16[0] == BZIP2_MAGIC
 193         ) {
 194                 xstate->xformer = unpack_bz2_stream;
 195                 USE_FOR_NOMMU(xstate->xformer_prog = "bunzip2";)
 196                 goto found_magic;
 197         }
 198         if (ENABLE_FEATURE_SEAMLESS_XZ
 199          && magic.b16[0] == XZ_MAGIC1
 200         ) {
 201                 xstate->signature_skipped = 6;
 202                 xread(fd, magic.b32, sizeof(magic.b32[0]));
 203                 if (magic.b32[0] == XZ_MAGIC2) {
 204                         xstate->xformer = unpack_xz_stream;
 205                         USE_FOR_NOMMU(xstate->xformer_prog = "unxz";)
 206                         goto found_magic;
 207                 }
 208         }
 209
 210         /* No known magic seen */
 211         if (fail_if_not_compressed)
 212                 bb_error_msg_and_die("no gzip"
 213                         IF_FEATURE_SEAMLESS_BZ2("/bzip2")
 214                         IF_FEATURE_SEAMLESS_XZ("/xz")
 215                         " magic");
 216
 217         /* Some callers expect this function to "consume" fd
 218          * even if data is not compressed. In this case,
 219          * we return a state with trivial transformer.
 220          */
 221 //      USE_FOR_MMU(xstate->xformer = copy_stream;)
 222 //      USE_FOR_NOMMU(xstate->xformer_prog = "cat";)
 223         /* fall through to seeking bck over bytes we read earlier */
 224
 225  found_magic:
 226         return xstate;
 227 }
 228
 229 /* Used by e.g. rpm which gives us a fd without filename,
 230  * thus we can't guess the format from filename's extension.
 231  */
 232 int FAST_FUNC setup_unzip_on_fd(int fd, int fail_if_not_compressed)
 233 {
 234         transformer_state_t *xstate = setup_transformer_on_fd(fd, fail_if_not_compressed);
 235
 236         if (!xstate || !xstate->xformer) {
 237                 free(xstate);
 238                 return 1;
 239         }
 240
 241 # if BB_MMU
 242         fork_transformer_with_no_sig(xstate->src_fd, xstate->xformer);
 243 # else
 244         /* NOMMU version of fork_transformer execs
 245          * an external unzipper that wants
 246          * file position at the start of the file.
 247          */
 248         xlseek(fd, - xstate->signature_skipped, SEEK_CUR);
 249         xstate->signature_skipped = 0;
 250         fork_transformer_with_sig(xstate->src_fd, xstate->xformer, xstate->xformer_prog);
 251 # endif
 252         free(xstate);
 253         return 0;
 254 }
 255
 256 static transformer_state_t *open_transformer(const char *fname, int fail_if_not_compressed)
 257 {
 258         transformer_state_t *xstate;
 259         int fd;
 260
 261         fd = open(fname, O_RDONLY);
 262         if (fd < 0)
 263                 return NULL;
 264
 265         if (ENABLE_FEATURE_SEAMLESS_LZMA) {
 266                 /* .lzma has no header/signature, can only detect it by extension */
 267                 char *sfx = strrchr(fname, '.');
 268                 if (sfx && strcmp(sfx+1, "lzma") == 0) {
 269                         xstate = xzalloc(sizeof(*xstate));
 270                         xstate->src_fd = fd;
 271                         xstate->xformer = unpack_lzma_stream;
 272                         USE_FOR_NOMMU(xstate->xformer_prog = "unlzma";)
 273                         return xstate;
 274                 }
 275         }
 276
 277         xstate = setup_transformer_on_fd(fd, fail_if_not_compressed);
 278
 279         return xstate;
 280 }
 281
 282 int FAST_FUNC open_zipped(const char *fname, int fail_if_not_compressed)
 283 {
 284         int fd;
 285         transformer_state_t *xstate;
 286
 287         xstate = open_transformer(fname, fail_if_not_compressed);
 288         if (!xstate)
 289                 return -1;
 290
 291         fd = xstate->src_fd;
 292         if (xstate->xformer) {
 293 # if BB_MMU
 294                 fork_transformer_with_no_sig(xstate->src_fd, xstate->xformer);
 295 # else
 296                 xlseek(fd, - xstate->signature_skipped, SEEK_CUR);
 297                 xstate->signature_skipped = 0;
 298                 fork_transformer_with_sig(xstate->src_fd, xstate->xformer, xstate->xformer_prog);
 299 # endif
 300         }
 301         /* else: the file is not compressed */
 302
 303         free(xstate);
 304         return fd;
 305 }
 306
 307 void* FAST_FUNC xmalloc_open_zipped_read_close(const char *fname, size_t *maxsz_p)
 308 {
 309 # if 1
 310         transformer_state_t *xstate;
 311         char *image;
 312
 313         xstate = open_transformer(fname, /*fail_if_not_compressed:*/ 0);
 314         if (!xstate) /* file open error */
 315                 return NULL;
 316
 317         image = NULL;
 318         if (xstate->xformer) {
 319                 /* In-memory decompression */
 320                 xstate->mem_output_size_max = maxsz_p ? *maxsz_p : (size_t)(INT_MAX - 4095);
 321                 xstate->xformer(xstate);
 322                 if (xstate->mem_output_buf) {
 323                         image = xstate->mem_output_buf;
 324                         if (maxsz_p)
 325                                 *maxsz_p = xstate->mem_output_size;
 326                 }
 327         } else {
 328                 /* File is not compressed */
 329                 image = xmalloc_read(xstate->src_fd, maxsz_p);
 330         }
 331
 332         if (!image)
 333                 bb_perror_msg("read error from '%s'", fname);
 334         close(xstate->src_fd);
 335         free(xstate);
 336         return image;
 337 # else
 338         /* This version forks a subprocess - much more expensive */
 339         int fd;
 340         char *image;
 341
 342         fd = open_zipped(fname, /*fail_if_not_compressed:*/ 0);
 343         if (fd < 0)
 344                 return NULL;
 345
 346         image = xmalloc_read(fd, maxsz_p);
 347         if (!image)
 348                 bb_perror_msg("read error from '%s'", fname);
 349         close(fd);
 350         return image;
 351 # endif
 352 }
 353
 354 #endif /* SEAMLESS_COMPRESSION */